Method of fitting an assembly formed of a tire and of a tread strip support

ABSTRACT

A method of fitting a tire and support ring on a one-piece wheel rim in  wh the rim includes a first wheel rim seating surface and a second wheel rim seating surface, the first wheel rim seating surface tapering outwardly and having a small hump at the axially outer end and being connected axially on the inside to a cylindrical portion intended to receive a tread support ring, the tire having a first bead and a second bead to be fitted, respectively, on the first wheel rim seating surface and the second wheel rim seating surface, and in which the removable support ring is inserted into the tire before fitting the support ring on the wheel rim.

BACKGROUND OF THE INVENTION

The subject of the present invention is a method of fitting, on a wheelrim which is in service, an assembly formed, on the one hand, by aradial tire and, on the other hand, by a removable ring for supportingthe tread, and more particularly an assembly intended on be fitted on aone-piece wheel rim, at least one of the seating surfaces of which istapered outwardly.

As described in unpublished French applications FR 92/15061, FR 93/14702and FR 93/14703, a rolling assembly which exhibits high performance whenrunning at low pressure or even at no pressure includes a rim having, insection through the middle, a first seating surface, the axially outerend of which is on a circle of diameter smaller than the diameter of thecircle on which the axially inner end is located (such a seating surfaceis said to taper outwardly), a bearing surface intended to receive aremovable ring for supporting the tread, possibly a well, and a secondseating surface which is either identical to or different than the firstseating surface, together with a tire of appropriate carcassreinforcement meridian profile having beads of appropriate shapes and aremovable support ring.

The nominal diameters of these seating surfaces may be equal, but theyare preferably unequal.

French Application FR 92/15061 describes a method of fitting a tire to awheel rim of the type in question. Said method consists first of all infitting one bead on the rim and sliding it as far as the well, theninserting the support ring, which is removable and rubbery, in theovalized state and then sliding it on the cylindrical bearing surfaceprovided for this purpose.

This method limits the axial width of the support, and it is not veryeasy to carry out in garages equipped with conventional tooling.

SUMMARY OF THE INVENTION

In order to overcome such drawbacks and improve the ease with which thetire, having a first bead and a second bead, and the removable supportring are mounted on a one-piece wheel rim comprising a first wheel rimseating surface and a second wheel rim seating surface, at least thefirst wheel rim seating surface tapering outwardly, extended axially onthe outside by a small hump, and connected axially on the inside to abearing surface intended to receive the tread support ring, the secondwheel rim seating surface having its axially inner end on a circle ofdiameter greater than the diameter of the circle on which the axiallyinner end of the first wheel rim seating surface is located, the methodof fitting, in accordance with the invention, comprising:

first of all, inserting the support ring inside the tire,

then placing the second bead onto the wheel rim from the side oppositeto the second wheel rim seating surface, then moving it on the wheel rimbearing surface using positioning means,

fitting the first bead on the first wheel rim seating surface, and

then carrying out the remaining stages of fitting the tire on the wheelrim.

The fitting of a tire on a wheel rim always begins by placing the tireon one side of the wheel rim and, by convention of language, the beadplaced first on the rim is referred to as the second bead, that is tosay, the bead which will be mounted on the wheel rim seating surfacesituated on the side opposite to the side from which mounting is begun,said wheel rim seating surface being the second wheel rim seatingsurface.

Before it is inserted into the tire, the support ring has to be in aform which allows its insertion; thus the support may be ovalized suchthat the short axis of the oval obtained after deformation is smallerthan the diameter of the tire bead seating surface over which thesupport has to pass; it may be puckered so that the maximum distancebetween two of its points is less than the diameter of said tire bead;it may retain its initial shape, it then being necessary to deform saidtire bead.

The means for positioning the bead vary depending on the shape of thewheel rim in service and depending on the axial width of the support. Ifthe nominal diameter of the second wheel rim seating surface is equal tothe nominal diameter of the first wheel rim seating surface, then thewheel rim generally has a well, and placing the second tire bead ontothe wheel rim and moving it along the wheel rim bearing surface, which,for example, is cylindrical, requires mechanical means, such as knowntire levers, rollers applied to the beads, or a tire press. By contrast,if the nominal diameter of the second wheel rim seating surface isgreater than that of the first seating surface, and in cases where thesupport has a width which is smaller than the axial distance separatingthe two beads after fitting, then the means for positioning the secondbead may be reduced simply to pressing it in the axial direction of thetire/support assembly.

Irrespective of the type of wheel rim considered in the presentinvention, in order to make it easier to position the first bead on thefirst wheel rim seating surface, it is advantageous to place a circularmetal ring with a frustoconical radially outer generatrix adjacent andaxially on the outside of said first seating surface.

DESCRIPTION OF THE DRAWINGS

The invention is illustrated by the drawings attached to thedescription, showing the various stages of fitting on several wheelrims, in which drawings:

FIGS. 1A to 1C diagrammatically represent the stage which is common tothe various types of fitting irrespective of the wheel rim, andillustrating three possible shapes of the support before insertion,

FIGS. 2A to 2D diagrammatically represent the subsequent stages in thecase of a wheel rim according to a first embodiment,

FIGS. 3A to 3C diagrammatically represent the subsequent stages in thecase of a wheel rim according to a second embodiment,

FIGS. 4A and 4B, still diagrammatically, represent the same stages inthe case of a wheel rim according to another embodiment,

FIG. 5 shows diagrammatically the presence of a circular ring axially onthe same side as the first wheel rim seating surface.

DESCRIPTION OF PREFERRED EMBODIMENTS

Shown in FIGS. 1A to 1C is the first operation, in accordance with theinvention, of fitting, on the wheel rim in question, a tire P which hasa construction, particularly as regards the beads, suited for fitting onthe wheel rim. The support ring S is inserted into the tire P. In thecase of FIG. 1A, the-support ring S has been ovalized beforehand bypressure at two points B, and C which are radially on the outside anddiametrically opposed, so that the distance X separating said two pointsis smaller than the initial outside diameter of the support ring andsmaller than the diameter D of the seating surface for the bead of thetire P. The support ring is thus inserted inside the tire P at rightangles to the plane of the bead wires. In the case of FIG. 1B, thesupport ring S, before being inserted into the tire P, is puckered bypressure at a single point B on its outside circumference so thatapproximately half the support is folded in its own plane into the otherhalf, which makes it possible to achieve a maximum straight-linedistance L between two points on the outside circumference of thesupport which is smaller than the diameter D of the seating surface forthe bead of the tire P. Insertion into the tire P then takes placeparallel to the plane of the bead wires. It is clear that in the twoexamples described hereinabove, the support ring S has to be made of amaterial which allows the deformations described; it is thereforeadvantageously made of a vulcanizable elastomeric material. It ispossible to use a support ring S made of a more rigid material,particularly a plastic material. Figure 1C shows how the support ring isinserted into the tire P: the support ring S is placed at right anglesto the plane containing the beads wires and the support ring is insertedinto the tire after said bead wires and the beads which contain themhave been ovalized.

In FIGS. 2A to 2D, the wheel rim J comprises, on each side of itsequatorial plane, and in section through the middle, a first wheel rimseating surface 21' and a second wheel rim seating surface 21" whichtaper outwardly, that is to say, the axially outer ends of the seatingsurfaces are on circles with diameters smaller than the diameters of thecircles on which the axially inner ends are to be located, these twoseating surfaces 21' and 21" having small humps 22' and 22" at theiraxially outer ends which are intended to retain the beads. The firstseating surface 21' is joined axially on the inside to a cylindricalportion 20 of the wheel rim, this portion being intended to receive thesupport ring S, for example made of a vulcanized rubbery compound, whilethe second wheel rim seating surface 21" is joined axially on the insideto a wheel rim flange 24. Said flange 24 together with the cylindricalportion 20 provided with a positioning hump 25 on its axially inner enddefine a well 23. The two wheel rim seating surfaces 21' and 21" in thenonlimiting example described have unequal diameters, the diameter ofthe axially inner end of the seating surface 21" being slightly greaterthan the diameter of the axially inner diameter of the seating surface21', the difference being 16 mm.

After the support ring S has been inserted into the tire P, the assemblythus formed is fitted on the wheel rim J by placing the second bead 2"on the rim from the side opposite to the side having the wheel rimflange 24, the position shown in the diagram of FIG. 2A, in which thesecond bead is in the well 23. Next, the first bead 2' of the tire P isfitted onto its seating surface 21' (FIG. 2B), for example, by usingtire levers, the second bead 2" still being in the well 23. Fitting isthen completed by raising the second bead 2" out of the well and movingit axially over the outside of the hump 22" bordering the second wheelrim seating surface 21' (FIG. 2C), then by placing said second bead 2"on its wheel rim seating surface 21" so that the tire P, the wheel rim Jand the support ring S are assembled as shown in FIG. 2D. The fittingoperation is then completed by inflating the assembly.

Another alternative form in accordance with the invention is illustratedin FIGS. 4A and 4B. This deals with fitting on a wheel rim J of the typein question, but the rim has neither a well nor an axially inner wheelrim flange, it being possible for said wheel rim J to have either twooutwardly tapered seating surfaces, or a first outwardly tapered seatingsurface and a second inwardly tapered or flat seating surface. A wheelrim seating surface is said to taper inwardly when its axially inner endis on a circle of diameter smaller than the diameter of the circle onwhich its axially outer end is located. A wheel rim seating surface issaid to be flat when its generatrix is parallel to the axis of rotationof the wheel rim. The example described deals with fitting on a wheelrim comprising a first outwardly tapered wheel rim seating surface 21',equipped axially on the outside with a hump 22', and a second outwardlytapered wheel rim seating surface 21" equipped axially on the outsidewith a hump 22". The first seating surface 21' is joined axially on theinside to a cylindrical portion 20. The second seating surface 21",which has an axially inner end on a circle of diameter greater than thediameter of the circle on which the axially inner end of the first wheelrim seating surface 21' is located, is connected axially on the insideby a frustoconical surface 26 forming a connection with the cylindricalportion 20. As in the alternative forms illustrated hereinabove, thefirst stage in the fitting method consists in inserting the treadsupport ring S into the tire P, it being possible for said support to bevery wide, for example as wide as the axial distance separating the twobeads of the tire fitted-on the wheel rim. The second stage consistssimply in slipping the assembly thus formed over the cylindrical portionof the wheel rim (FIG. 4A). The third stage consists in fitting thefirst bead 2' on its seating surface 21' (FIG. 4B) using a press, forexample, without concern about the placing of the second bead 2" whichis automatically positioned on its wheel rim seating surface. As in allthe cases, the last step consists in inflating the tire.

Fitting operations (not shown) the same as those described hereinaboveand shown in FIGS. 4A and 4B are possible in the case where the wheelrim for fitting, without a well and having a cylindrical portion 20 of awidth equal to the axial distance separating the two beads fitted on thewheel rim, have a second inwardly tapered wheel rim seating surface 21"and the axially inner end of which is on a circle of diameter at leastequal to the diameter of the circle on which the axially inner end ofthe first wheel rim seating surface 21' is located, and a radiallyextending wheel rim flange of configuration similar to that of known,normal and standardized wheel rim flanges located adjacent the outer endof the second seating surface.

It is possible to use a wheel rim J as shown in FIG. 3 of theunpublished application FR 93/14703, that is to say a wheel rim J of thetype in question, which does not have a well and has a cylindricalportion 20 equipped axially on the inside with a projection 25 forpositioning the support ring S and with an inwardly tapered second wheelrim seating surface 21". This second wheel rim seating surface 21" is,on the one hand, joined axially on the inside to a projection 27 forretaining the second bead 21' and extended axially on the outside by aconventional wheel rim flange 24. In this case too, after the treadsupport S has been inserted into the tire P, the assembly is slippedonto the wheel rim J (FIG. 3A) and the first bead 2' is fitted on thefirst wheel rim seating surface 21' without concern about the positionof the second bead 2" (FIG. 3B), the pressurizing of the interior cavityof the tire acting as a device for positioning the second bead, so as toreach the fitted assembly (FIG. 3C).

FIG. 5 illustrates the possibility of juxtaposing an auxiliary ring Afor positioning the first bead 2' on its wheel rim seating surface 21'axially next to the first hump 22' of the wheel rim. This ring A has atransverse section, the radially outer side 30 of which is afrustoconical generatrix. Said frustoconical generatrix 30 has anaxially inner end on a circle of diameter .o slashed. equal to themaximum diameter Ds of the radially outer face of the axially adjacenthump 22', and an axially outer end of a circle of diameter smaller than.o slashed., so that it makes an angle of between 5° and 20° with thedirection parallel to the axis of rotation of the whole. Said removablering is fixed to the wheel rim J by any known fixing means such aswelding, possibly combined with screw-fastening, for example.

As regards the removal of an assembly formed by the tire and the treadsupport, this presents no difficulties irrespective of the wheel rimused. Pressure on the second bead using appropriate equipment, theamount of pressure depending on the configuration of wheel rim, allowssaid bead to be dislodged so as to bring it axially to the inside.Dislodging the first bead from its wheel rim seating surface poses noadditional problems since in the same way all that is required is for asimple pressure to be exerted on its wall, using simple tools.

What is claimed is:
 1. A method of fitting a tire and a tread supportring on a one-piece wheel rim comprising a first wheel rim seatingsurface, a second wheel rim seating surface, a tread support ringbearing surface connected axially on the inside of the first wheel rimseating surface and a small hump at the outer end of the first wheel rimseating surface, at least the first wheel rim seating surface taperingoutwardly and the second wheel rim seating surface having its axiallyinner end on a circle of a diameter greater than the diameter of thecircle on which the axially inner end of the first wheel rim surface islocated, the tire comprising a first bead (2') and a second bead (2")which will surface is located, the tire comprising a first bead (2') anda second bead (2") which will be fitted respectively on the first wheelrim seating surface and the second wheel rim seating surface, the methodcomprising:in a first stage, inserting the support ring into the tire,placing the second bead (2") onto the wheel rim from the side oppositeto the second wheel rim seating surface and moving it over the bearingsurface using positioning means, fitting the first bead on the firstwheel rim seating surface, the first bead engaging the support ring toseat it on the bearing surface, and then completing the fitting of thesecond bead on the second wheel rim seating surface.
 2. A methodaccording to claim 1, including ovalizing the support ring by pressureat two diametrically opposed points before it is inserted into the tire,said insertion taking place at right angles to the plane of the beadwires on the beads.
 3. A method according to claim 1, includingpuckering the support ring before it is inserted into the tire, saidinsertion taking place parallel to the plane of the bead wires in thebeads.
 4. A method according to claim 1, including ovalizing the beadwires of the beads and inserting the support ring into the tire at rightangles to the plane of the bead wires.
 5. A method according to claim 1in which the wheel support ring bearing surface is cylindrical and therim includes a hump for positioning the support ring on the bearingsurface, the second wheel rim seating surface is tapered outwardly andthe axially inner end is on a circle of diameter greater than thediameter of the circle on which the axially inner end of the first wheelrim seating surface is located and in which the completing of thefitting of the second bead on the second wheel rim seating surfacecomprises:displacing the second bead axially beyond the cylindricalbearing surface and radially to the outside of the wheel rim, fittingthe second bead on the second wheel rim seating surface, inflating thetire.
 6. A method according to claim 5, in which the rim includes atleast one well, a radially extending flange between the well and thesecond seating surface and the method includes inserting the second beadinto the well after the second bead has been placed on the wheel rim. 7.A method according to claim 1 in which the fitting of the second bead onthe second wheel rim seating surface is completed byselecting a supportring of a width which spans the distance between the beads, pushing theassembly of tire and support ring until the first bead is in position onthe first wheel rim seating surface, the second bead positioning itselfon the second wheel rim seating surface under the effect of the axialdisplacement of the support, inflating the tire.
 8. A method accordingto claim 7 in which a hump is provided axially to the outside of thesecond wheel rim seating surface and a frustoconical surface connectsthe cylindrical bearing surface and the second wheel rim seatingsurface.
 9. A method of fitting according to claim 7 in which the secondwheel rim seating surface has a radially extending flange at the axiallyouter end and the surface of the second wheel rim seating surface tapersinwardly from the flange.
 10. A method according to claim 1, includingplacing adjacent the hump at the outer end of the first wheel rimseating surface a metal circular ring having, in meridian section, aradially outer surface which is a frustoconical generatrix forming anangle of between 5° and 20° with the direction parallel to the axis ofthe rim, the axially inner end of which is on a circle of diameter equalto the maximum diameter of the said hump, joining the metal ring to thewheel rim by fastening means, and sliding the assembled tire and supportring along the metal ring onto the rim.
 11. A method according to claim10, including removing the metal ring from the rim when the tire andsupport ring are fitted on the rim.